The present invention relates to paperboard processing equipment and more particularly to an apparatus for feeding paperboard sheets to printers, cutters, slotters, gluers and the like.
Various types of processing equipment are used in the manufacture of paperboard packaging, including printers, cutters, slitters and gluers. The equipment is used to manufacture a wide variety of boxes and special packaging from sheets of paperboard. Generally, individual sheets of paperboard are fed into the processing equipment manually or by automatic sheet feeders.
Heretofore, various sheet feeders have been proposed. Typically, these feed individual sheets from a stack to the feed rolls of the processing equipment. Problems experienced with prior proposals include excessive wear, complexity and difficulties with setup. It is important to minimize maintenance downtime in order to maintain production rates.
An example of one prior approach is found in U.S. Pat. No. 4,045,015 entitled ROTARY FEEDER FOR PAPERBOARD BLANKS and issued on Aug. 30, 1977, to Sardella. The rotary feeder disclosed in this patent includes a plurality of configured feed wheels. Each wheel has an active portion and a relieved portion. A transmission brings the active portion of the feed wheels into contact with the underside of a sheet of paperboard. The sheet is accelerated to match the speed of the feed rolls of the processing equipment. As the sheet is pulled into the feed roll, the wheels move out of contact with the paperboard sheet. The transmission must transmit rotary input motion so that the feed wheels are initially accelerated, then decelerated and then held stationary.
Another example of a sheet feeder is found in U.S. Pat. No. 4,494,745 entitled FEEDING APPARATUS FOR PAPERBOARD SHEETS and issued on Jan. 22, 1985, to Ward et al. The feeding apparatus disclosed in this patent includes a plurality of feed belts. The belts are brought into contact with the sheet and then actuated to bring the sheet to the feed rolls of the processing equipment. The belts are then moved out of contact with the paperboard sheet before their motion is stopped. The intermittent driving of the belts must be synchronized with the operation of lift bars which move the belts into and out of contact with the paperboard sheet.
A still further example of a paperboard sheet feeder includes a feed table which supports a plurality of feed wheels. The wheels are covered with a polyurethane material. A drive arrangement rotates the wheels to feed sheets. A low friction sliding grid is raised as the sheet is fed to the nip of the feed rolls. The grid keeps the sheet out of contact with the feed wheels as the sheet is drawn into the processing equipment by the feed rolls.
A need exists for a reliable sheet feeder of reduced complexity and increased reliability and which may be readily added at the feed ends of existing paperboard processing equipment.